Wyoming Premium Farms Abuse Alleged By Humane Society (GRAPHIC VIDEO)

Piglets are haphazardly swung in circles, sows are beaten, and animals squirm with untreated abscesses in new footage alleging animal abuse at a Wyoming pig breeding facility.

The Humane Society of the United States (HSUS), an animal advocacy group, hired an undercover investigator to spend the month of April 2012 working at a Wyoming Premium Farms facility in Wheatland, Wyo.

HSUS identified one pig in its video on whose back, it said, a worker sat and bounced even though the pig had a broken leg. Other animals suffered from rectal and uterine prolapses.

Wayne Pacelle, president and CEO of HSUS, described on a press call how one pig was forced to give birth on a set date. "The worker intended to stick his arm in the animal's uterus to pull out the piglets, but instead went into her anus and caused the prolapse there. This animal lived another 11 days in this condition," he said.

According to HSUS, the farm is owned by Denver-based Itoham America Inc., which HSUS says sells to Tyson Foods, the world’s second largest meat processor. Itoham America could not be reached by phone.

Last week, HSUS said, it notified local authorities of the alleged abuse and urged the Platte County sheriff’s office to pursue criminal charges. The sheriff's office did not return HuffPost's request for comment, but Pacelle said he was "very pleased with their interest and their degree of scrutiny."

Wyoming Premium Farms' website states that its facilities "consist of a breeding farm housing over 5,000 sows, a nursery and two finishers with capacity to finish all pigs, feedmill to mix all feed required and a corporate office." The farms were established in 1995 "with the purpose of producing healthy pigs in a clean environment." The company did not return requests for comment.

Tyson Foods spokesman Worth Sparkman emailed a statement to HuffPost, saying the company was "appalled" by the video and denying any connection between the Wyoming farm and the pork processed by Tyson. "Tyson Foods does not buy any of the hogs raised on this farm for our pork processing plants. We do have a small, but separate hog buying business that buys aged sows; however, these animals are subsequently sold to other companies and are not used in Tyson’s pork processing business," the statement said.

Sparkman clarified in a follow-up email: "A company that we own has purchased hogs from the farm. We will not purchase from this farm until we've had a chance to investigate."

The original statement also says that all hog suppliers selling to Tyson must be certified by the pork industry’s Pork Quality Assurance Plus program, adding, "Farms that do not conform will be eliminated from our supply chain."

In April, HSUS filed a complaint with the Federal Trade Commission, arguing that the National Pork Producers Council's public descriptions of that quality assurance program make false claims and constitute deceptive advertising.

The National Pork Producers Council hit back on its website, saying, "The FTC complaint is the latest attack by animal-rights activists on America's hog farmers, an assault that seems obviously in response to the U.S. pork industry's strident opposition to congressional legislation that would allow federal bureaucrats to tell farmers how to raise and care for their animals."

To address both the specific alleged abuse at Wyoming Premium Farms and broader issues of animal welfare, Pacelle said, the pork industry should abandon the use of gestation crates -- small enclosures in which sows are kept during pregnancy -- and local law enforcement should vigorously enforce anti-cruelty laws.

McDonald’s, Wendy’s, Safeway and Burger King have all declared a goal of ridding gestation crates from their supply chains. Smithfield Foods, Hormel and Cargill are also making efforts to lower the number of company-owned operations using the devices. According to HSUS, eight U.S. states have passed laws to phase out gestation crates.

More generally, no federal law protects farm animals from cruelty while they are on farms, and some states exempt farm animals from their anti-cruelty laws. HSUS Chief Counsel Jonathan Lovvorn told HuffPost that Wyoming's law falls somewhere in the middle among anti-cruelty statutes. "The state's anti-cruelty statute applies to all animals, which is why the HSUS has asked local law enforcement to prosecute animal cruelty," he said, adding, "What we've seen on this video is animal cruelty by virtually any state's definition -- the intentional kicking, throwing, stomping, beating of animals for the purpose of inflicting pain and suffering."

Earlier this year, HSUS filed complaints with the Securities and Exchange Commission and the FTC after another undercover investigation suggested mistreatment at a pig breeding facility linked to Walmart. In an unrelated incident this year, Whole Foods severed ties with a hatchery after Compassion Over Killing's undercover video showed alleged abuse, although the company wouldn't say whether its decision was based on the abuse allegations.

The use of such videos to reveal abuses at factory farms is threatened. In March, Iowa made it illegal to gain access to a farm facility under false pretenses, and other states have considered similar laws.

"If those laws existed [in Wyoming]," Lovvorn argued, "the cruelty at this facility would have continued forever with no public knowledge, no law enforcement and no remedial action."